In accordance with the laws of thermodynamics, it is desirable to provide an engine which maximizes pressure and temperature during combustion, as such results in the most efficient conversion of energy. In addition, in accordance with the laws of physics, the power to weight ratio of an engine increases as the speed of engine operation increases.
Unfortunately, a variety of secondary effects make difficult the achievement of an engine which achieves these objectives. As engine speed increases, so do the inertial forces and the stresses placed upon moving parts in the engine. At high speeds, the failure rate of these parts increases. Increasing the size of these parts to increase their strength has limited benefits, as such further increases the inertial forces and the total weight of the engine.
In some instances, current engine designs also do not permit ready solutions to these problems. For a number of reasons, traditional piston rods are much longer than the distance of the entire piston stroke. One advantage arising from a longer piston rods is such permits a longer piston stroke, and thus a higher compression ratio. The longer piston rod also provides greater clearance between the piston and crankshaft at bottom dead center. On the other hand, the longer piston rod is subject to high inertial forces.
A problem with raising engine temperatures and pressures is that the life of parts subjected to these high heat and pressures in the engine are reduced. In order to reduced the detrimental effects of the high heat, today's engines employ cooling systems. The cooling systems, however, serve to reduce the efficiency of the system.
Another problem with an engine operating at high speed is that the time for combustion is very short. To accommodate combustion time, combustion may be initiated before the piston is at top dead center. Combustion forces generated as the piston moves upwardly to top dead center act against the direction of the piston, contributing to a lower energy level of the engine. On the other hand, if combustion is not initiated until the piston is at top dead center, then total optimum combustion time is very short. As a result, the generated combustion force is limited, and so is the power output of the engine in relation to provided fuel.
Another disadvantage of a short combustion time is that certain less combustible alternative fuels are not usable in these engines. Simply, the combustion time is so short that slower combusting fuels do not sufficiently combust to generate efficient engine power. A problem with existing engines is that the optimal combustion time is so short, that it is detrimental to raise the speed of the engine because optimal combustion time is further shortened. This problem thus prevents achievement of an engine with otherwise higher efficiency by operation at higher speeds.
Two-cycle internal combustion engines have an advantage over four-cycle internal combustion engines in that an entire piston cycle is not lost without producing force. On the other hand, combustion effects are reduced due to incomplete scavenging: not all of the exhaust gasses are exhausted before combustion initiates, and insufficient incoming air is provided for complete combustion of the fuel.
One detrimental side effect of this incomplete combustion of fuel is the exhausting of unburned fuel and undesirable gasses. Due to the emission problems associated with two-cycle engines, in some instances U.S. laws prevent the operation of two-cycle engines.
Another problem with existing engines is that they are not suited to miniaturization and for use not only as prime movers, but as compressors and pumps. In particular, the current design of internal combustion engines, including by reason of having so many moving parts, is not suited to such adaptation.
An engine which is capable of exploiting the advantages of high pressures of combustion, high temperatures of combustion, and high engine speed is desired, as is an engine having minimal moving parts, such as one having no crankshaft or connecting rods, which is thus suited for miniaturization.